Method of forming a head suspension with an integral boss tower

ABSTRACT

A method of making a multi-piece head suspension for a rigid disk drive. The method includes providing a first layer including a mounting region with an integral boss tower attached to a stiffener by one or more positioning tabs; attaching a second layer including a spring region to an interface between the mounting region and the stiffener; attaching a flexure to the stiffener; and removing the positioning tabs. The flexure can optionally be a portion of the second layer.

This application is a divisional of U.S. patent application Ser. No.10/768,296, filed Jan. 30, 2004 entitled Method of Forming A HeadSuspension With An Integral Boss Tower (Allowed), which is a divisionalof U.S. patent application Ser. No. 10/093,222 filed Mar. 6, 2002,issued as U.S. Pat. No. 6,728,072 on Apr. 27, 2004, entitled IntegralBase Plate With Boss Tower, which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/273,749 filed Mar. 6, 2001.

FIELD OF THE INVENTION

The present invention is directed to a method of forming a headsuspension assembly having a mounting region with an integral bosstower, and to a multi-piece head suspension assembly with an integralboss tower.

BACKGROUND OF THE INVENTION

In a dynamic rigid disk storage device, a rotating disk is employed tostore information. Rigid disk storage devices typically include a frameto provide attachment points and orientation for other components, and aspindle motor mounted to the frame for rotating the disk. A read/writehead is formed on a “head slider” for writing and reading data to andfrom the disk surface. The head slider is supported and properlyoriented in relationship to the disk by a head suspension that providesboth the force and compliance necessary for proper head slideroperation. As the disk in the storage device rotates beneath the headslider and head suspension, the air above the disk also rotates, thuscreating an air bearing which acts with an aerodynamic design of thehead slider to create a lift force on the head slider. The lift force iscounteracted by a spring force of the head suspension, thus positioningthe head slider at a desired height and alignment above the disk that isreferred to as the “fly height.”

Head suspensions for rigid disk drives include a load beam and aflexure. The load beam includes a mounting region at its proximal endfor mounting the head suspension to an actuator of the disk drive, arigid region, and a spring region between the mounting region and therigid region for providing a spring force to counteract the aerodynamiclift force generated on the head slider during the drive operation asdescribed above. The flexure typically includes a gimbal region having aslider-mounting surface where the head slider is mounted. The gimbalregion is resiliently moveable with respect to the remainder of theflexure in response to the aerodynamic forces generated by the airbearing. The gimbal region permits the head slider to move in pitch androll directions and to follow disk surface fluctuations.

In one type of head suspension, the flexure is formed as a separatepiece having a load beam-mounting region that is rigidly mounted to thedistal end of the load beam using conventional methods such as spotwelds. Head suspensions of this type typically include a load pointdimple formed in either the load beam or the gimbal region of theflexure. The load point dimple transfers portions of the load generatedby the spring region of the load beam to the flexure, provides clearancebetween the flexure and the load beam, and serves as a point about whichthe head slider can gimbal in pitch and roll directions to followfluctuations in the disk surface.

The actuator arm is coupled to an electromechanical actuator thatoperates within a negative feedback, closed-loop servo system. Theactuator moves the data head radially over the disk surface for trackseek operations and holds the transducer directly over a track on thedisk surface for track following operations.

The preferred method of attaching the head suspension to the actuatorarm is swaging because of the speed and cleanliness of the swagingprocess. Swaging also provides a strong joint that resists microslip.The swaging process has been in use in rigid disk drives since the late1 960s for attaching head-suspension assemblies to actuator arms.

FIG. 1 is an exploded, isometric view of a conventional head stackassembly 10 including a load beam 12, an actuator arm 32 and a discretebase plate 24 with a boss tower 28. The head suspension assembly 10includes a load beam 12 with a flexure 16 to which a head slider 20having a read/write element or head is to be mounted. The load beam 12includes a mounting region 14 at a proximal end, a rigid region 22adjacent to a distal end, and a spring region 18 between the mountingregion 14 and rigid region 22. Spring region 18 is relatively resilientand provides a downward bias force at the distal tip of load beam 12 forholding the read/write head near a spinning disk in opposition to anupward force created by an air bearing over the disk. The flexure 16 isto allow pitch and roll motion of head slider 20 and read/write head asthey move over the data tracks of the disk. The head suspension assembly10 is typically coupled to the actuator via the actuator arm 32 that isattached to the mounting 14 region of load beam 12.

A swage type attachment is used to couple the mounting region 14 of theload beam 12 to the actuator arm 32. To swage load beam 12 to actuatorarm 32, actuator arm 32 and mounting region 14 include apertures 34 and26, respectively. The base plate 24 having a boss tower 28 with a swagehole 30 extending therethrough and, typically, a square flange 36 iswelded or otherwise attached to a bottom face of mounting region 14 ofload beam 12. Boss tower 28 is then inserted through actuator armaperture 34. One or more swage balls are then forced through swage hole30 in boss tower 28 causing boss tower 28 to expand in actuator armaperture 34. This expansion creates a frictional attachment interfacebetween outside surface 66 of boss tower 28 and interior surface 68 ofactuator arm aperture 34. The load beam 12 typically includes one ormore processing holes 38 useful for aligning the load beam 12 with thebase plate 24 and/or actuator arm 32. The base plate 24 and/or actuatorarm 32 may optionally include corresponding processing holes 38a, 38b tofacilitate alignment.

The design of the swage joint has been reduced in size to keep up withthe miniaturization of disk drives. As the industry pushes to decreasedisk spacing and to increase aerial spacing, the thickness of the baseplate 24 and actuator arm 32 are constantly being decreased. However,recent moves to disk-to-disk spacing of under two millimeters havepresented a severe problem. Miniaturization of the swage plates is notsatisfactory because the torque-out capability that the swaged systemdrops too low to be useful.

What is needed is an attachment system that reduces head stack thicknesswithout compromising torque-out capabilities.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a head suspension assembly with amounting region comprising an integral boss tower. The integral bosstower can be formed from material comprising the mounting region or as aseparate component attached directly to the mounting region without abase plate. The integral boss tower eliminates the base plate andreduces the size of the head stack assembly, and hence, reduces diskspacing. The elimination of the base plate also reduces mass and inertiaof the head suspension. The present integral boss tower can be used tomount a head suspension assembly to an actuator arm usingindustry-accepted standards.

The head suspension assembly comprises a load beam having a mountingregion, a rigid region, and a spring region located between the mountingregion and rigid region. The mounting region comprises an integral bosstower having an attachment feature. The integral boss tower can beformed from the material comprising the mounting region or attacheddirectly to the mounting region without a base plate.

The mounting region, the rigid region, and the spring region can be aunitary structure. Alternatively, the mounting region and the rigidregion can be separate components.

The present invention is also directed to a multi-piece head suspensionassembly with an integral boss tower. In one embodiment, the mountingregion and the rigid region comprise a first layer, and the springregion comprises a second layer in a multi-piece suspension. In anotherembodiment, the mounting region and the rigid region comprise a firstlayer, and the spring region and a flexure comprise a second layer in amulti-piece suspension. In yet another embodiment, the mounting regionand the rigid region comprise a first layer, the spring region comprisesa second layer, and the flexure comprises a third layer in a multi-piecesuspension.

The boss tower can be a separate component attached to mounting featureslocated in the mounting region, such as by welding, adhesive bonding orinjection molding the boss tower in place over formed or etched mountingfeatures. The mounting features can be a variety of structures, such astabs or holes. For example, the mounting features can be a plurality ofradial tabs formed adjacent to an aperture in the mounting regioncomprising at least one bend.

The present invention is also directed to a head stack assembly in arigid disk drive. The head stack assembly includes an actuator arm and ahead suspension assembly comprising a load beam having a mountingregion, a rigid region, and a spring region located between the mountingregion and rigid region. The mounting region comprises an integral bosstower having an attachment feature.

The present invention is also directed to a method of forming amulti-piece head suspension for a rigid disk drive comprising the stepsof providing a first layer including a mounting region with an integralboss tower attached to a stiffener by one or more positioning tabs;attaching a second layer including a spring region to an interfacebetween the mounting region and the stiffener; attaching a flexure tothe stiffener; and removing the positioning tabs. The flexure can be aportion of the second layer or a third layer.

The present invention is also directed to a method of forming amulti-piece head suspension for a rigid disk drive having a load beamwith a mounting region, a rigid region and a spring region locatedbetween the mounting region and rigid region, comprising the steps ofcreating a plurality of tabs adjacent to an aperture in the mountingregion; and making at least one bend in one or more tabs to generate anintegral boss tower. The tabs can optionally be created to extendradially inward toward a center of the aperture or a variety of otherconfigurations.

The present invention is also directed to a method of forming a headsuspension for a rigid disk drive having a load beam with a mountingregion, a rigid region, and a spring region located between the mountingregion and rigid region. The method comprises the steps of locating aplurality of mounting features adjacent to an aperture in the mountingregion; and attaching a boss tower to the mounting features. In oneembodiment, the step of attaching a boss tower to the mounting featurecomprises molding the boss tower in place.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a perspective view of a conventional head suspension assembly.

FIG. 2 is a perspective view of a head suspension assembly having amounting region with an integral boss tower in accordance with thepresent invention.

FIG. 3A is an exploded view of components for a multi-layered headsuspension assembly with a mounting region having an integral boss towerin accordance with the present invention.

FIG. 3B is a perspective view of a multi-layered head suspensionassembly constructed from the components of FIG. 3A.

FIG. 3C is a perspective view of a completed head suspension of FIG. 3B.

FIG. 4A is an exploded view of components for a multi-layered headsuspension assembly with a mounting region having an integral boss towerin accordance with the present invention.

FIG. 4B is a perspective view of a multi-layered head suspensionassembly constructed from the components of FIG. 4A.

FIG. 4C is a perspective view of a completed head suspension of FIG. 4B.

FIG. 5A is a top view of a mounting region of a load beam in accordancewith the present invention.

FIG. 5B is a perspective view of a boss tower integrally formed in themounting region of FIG. 5A.

FIG. 6 is a side sectional view of a boss tower attached to mountingfeatures and/or a mounting region in accordance with the presentinvention.

FIG. 7 is a top view of a mounting region with mounting features inaccordance with the present invention.

FIG. 8 is a top view of an alternate mounting region with mountingfeatures in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is an exploded, isometric view of a head stack assembly 111including a head suspension assembly 110 and an actuator arm 132. Thehead suspension assembly 110 includes a load beam 112 with a flexure 116to which a head slider 120 having a read/write element or head mountedat a slider mounting surface 150. Slider mounting surface 150 on flexure116 in combination with dimple 148 on distal end 146 allows pitch androll motion of head slider 120 and read/write head as they move over thedata tracks of the disk.

The load beam 112 includes a mounting region 114 at a proximal end, arigid region 122 adjacent to a distal end and a spring region 118between the mounting region 114 and rigid region 122. Spring region 118is relatively resilient and provides a downward bias force at the distaltip of load beam 112 for holding the read/write head 120 near a spinningdisk in opposition to an upward force created by an air bearing over thedisk.

The mounting region 114 includes an integral boss tower 128 accordancewith the present invention. In the embodiment of FIG. 2, the mountingregion 114, the spring region 118, the rigid region 122, and the bosstower 128 are all formed as a unitary structure from the same piece ofmaterial or layer. As used herein, “integral boss tower” refers to aboss tower formed from a portion of the discrete piece of materialcomprising the mounting region; a boss tower attached to the mountingregion without a base plate; or a combination thereof.

The integral boss tower can be created from the metal comprising themounting region 114 using a reduction or a non-reduction stamping orforming operation. In embodiments where the boss tower 128 is a separatecomponent, the boss tower 128 can be attached to the mounting region 114using adhesives, welding, fasteners, interconnecting features formed onthe boss tower 128 and/or the mounting region 114, or combinationsthereof. Suitable adhesives include pressure sensitive adhesives,thermosetting or thermoplastic adhesives, radiation cured adhesives,adhesives activated by solvents, and combinations thereof. In anotherembodiment, features formed on the mounting region 114 can serve as theboss tower or can be interengaged with a separately formed boss tower.In another embodiment, the boss tower can be injection molded in placeover formed or etched mounting features. As used herein, “mountingfeature” refers to aspects or structure in the mounting region thatfacilitates attachment of a boss tower. The boss tower can beconstructed from metals, polymeric materials, metal-polymer composites,ceramic-polymer composites, or a variety of other materials.

The boss tower 128 has one or more attachment features used to couplethe integral boss tower 128 on the mounting region 114 of a load beam toan actuator arm 132. As used herein, “attachment feature” refers to oneor more aspects or structures of a boss tower that facilitate attachmentto an actuator arm. In the illustrated embodiment, the attachmentfeature is a swage type attachment. To swage load beam 112 to actuatorarm 132, the boss tower 128 is inserted into the aperture 134 on theactuator arm. One or more swage balls are then forced through swage hole130 in boss tower 128 causing boss tower 128 to expand in actuator armaperture 134. This expansion creates a frictional attachment interfacebetween outside surface 166 of boss tower 128 and interior surface 168of actuator arm aperture 134.

Elimination of the base plate 24 of FIG. 1 significantly reduces thethickness of the head stack assembly 111 in the region adjacent to theactuator arm 132, permitting a reduction in disk spacing. This reductionin thickness can be achieved without reducing the surface area of theoutside surface 166 on the boss tower 128. The elimination of the baseplate also reduces mass and inertia of the head suspension 110.

FIGS. 3A-3C illustrate an alternate multi-piece head suspension assembly200 in accordance with the present invention. As best illustrated inFIG. 3A, the head suspension assembly 200 includes a mounting region 202with an integral boss tower 204. The mounting region 202 is releasablyattached to stiffener 206 by a pair of positioning tabs 208. Thestiffener 206 comprises the rigid region. A carrier strip 218 isoptionally attached to the mounting region 202. A typical carrier strip218 is typically attached to a plurality of mounting regions.

For high resonance performance, the stiffener 206, the boss tower 204and the mounting region 202 are preferably made from the same sheet orlayer 222 of material. The mounting region 202 and the stiffener 206remain tabbed together during assembly, which facilitates more accurateplacement of the components during assembly of the head suspension 200.

In the illustrated embodiment, spring region 210 is a separate componentthat is attached so as to extend across gap 212 between the mountingregion 202 and the stiffener 206. Flexure 214 and the spring region 210are made from the same sheet or layer 224 of material. The flexure 214illustrated in FIG. 3A includes a lead support 216 for supportingelectrical leads 220 to the slider (see FIG. 2).

The spring region and flexure layer 224 is stacked with the mountingregion and stiffener layer 222. The layers 222, 224 are joined by spotwelding, adhesives, or a variety of other techniques. Intermediatelayers, such as adhesive layers may be used. As best illustrated in FIG.3C, the positioning tabs 208 and the carrier strip 218 are then removedso as to free the spring region 210 to operate as intended.

FIGS. 4A-4C illustrates an alternate multi-piece head suspensionassembly 250 in which spring region 252 is a separate component or layer272 from the layer 274 comprising the flexure 254. Mounting region 256is attached to stiffener 258 by positioning tabs 260 in layer 276. Acarrier strip 268 is also shown. Mounting region 256 includes anintegral boss tower 262, as discussed above. The layers 272, 274, 276are aligned and joined together using any of the variety of the methodsdiscussed above. As best illustrated in FIG. 4C, the positioning tabs260 and the carrier strip 268 are removed forming gap 270.

FIG. 5A illustrates a mounting region 280 of a head suspension assembly(see FIG. 2) in which a series of slots 282 have been stamped or etchedadjacent to aperture 284. The slots 282 preferably extend radiallytoward the center of the aperture 284, although a variety of curvilinearor angled shapes can be used. The positioning of the slots 282 define aplurality of features or tabs 286. As illustrated in FIG. 5B, tabs 286formed by the slots 282 have a first bend 296, upwards in a firstdirection 288 forming a boss tower 294. Distal ends 290 of the tabs 286optionally have a second bend 298, downward in a direction 292, usefulto reinforce the boss tower 294. The tabs 286 comprise the attachmentfeature for attachment to an actuator arm (see FIG. 2).

In an alternate embodiment, a series of bends can be made in the tabs286 to attach a discrete boss tower to the mounting region 280. In oneembodiment, the tabs 286 are bent so that a discrete boss tower can snapfit or engage with the mounting region 280. In yet another embodiment, aboss tower can be injection molded directly over any of the tabconfigurations discussed above.

FIG. 6 is side sectional view of a mounting region 300 having mountingfeatures 302 formed adjacent to aperture 304. The mounting features 302can be etched and/or formed. The mounting features 302 may be continuousor discontinuous around aperture 304. Boss tower 306 can be attached tothe mounting features 302 and/or the mounting region 300 usingadhesives, welding, fasteners, interconnecting features formed on theboss tower 306 and/or the mounting features 302, or combinationsthereof. Suitable adhesives include pressure sensitive adhesives,thermosetting or thermoplastic adhesives, radiation cured adhesives,adhesives activated by solvents, and combinations thereof. In anotherembodiment, the boss tower 306 is injection molded in place over themounting features 302. In yet another embodiment, the boss tower 306 isattached to the mounting region 300 and the mounting features 302 serveprimarily to position and align the boss tower 306 relative to theaperture 304.

FIG. 7 illustrates an alternate mounting region 320 having a pluralityof holes 322 etched or formed around perimeter 324 of aperture 326. Theholes 322 facilitate attachment of a boss tower (see FIG. 6) to themounting region 300. The number, shape, orientation and spacing of theholes 322 can vary. In one embodiment, the holes 322 engage withmounting features on a boss tower in an interlocking or snap-fitconfiguration. In another embodiment, a boss tower is injection moldedto the mounting region 320 and the material from which the boss tower ismolded flows through and/or around the holes 322 to strengthen the bond.

FIG. 8 illustrates another alternate mounting region 340 having aplurality of tabs 342 etched or formed around perimeter 344 of aperture346. The tabs 342 facilitate attachment of a boss tower (see FIG. 6) tothe mounting region 340. The number, shape, orientation and spacing ofthe tabs 342 can vary. In one embodiment, the tabs 342 engage withmounting features on a boss tower in an interlocking or snap-fitconfiguration. In another embodiment, a boss tower is injection moldedto the mounting region 340 and the material from which the boss tower ismolded flows through and/or around the tabs 342 to strengthen the bond.

All patents and patent applications disclosed herein, including thosedisclosed in the background of the invention, are hereby incorporated byreference. Although the present invention has been described withreference to preferred embodiments, workers skilled in the art willrecognize that changes may be made in form and detail without departingfrom the spirit and scope of the invention. In addition, the inventionis not to be taken as limited to all of the details thereof asmodifications and variations thereof may be made without departing fromthe spirit or scope of the invention.

1. A method of forming a multi-piece head suspension for a rigid diskdrive, comprising the steps of: providing a first layer comprising amounting region with an integral boss tower attached to a rigid regionby at least one positioning tab; providing a second layer comprising aspring region; attaching the second layer to the first layer so at leasta portion of the spring region is located at an interface between themounting region and the rigid region; providing a flexure on the rigidregion; and removing the at least one positioning tab.
 2. The method ofclaim 1 wherein the rigid region comprises a stiffener.
 3. The method ofclaim 1 wherein the flexure comprises a portion of the second layer. 4.The method of claim 1 wherein the flexure comprises a portion of a thirdlayer.
 5. The method of claim 1 wherein the steps of providing a firstlayer comprising a mounting region with an integral boss tower,comprises the steps of: forming an aperture in the mounting region;creating at least one projecting portion integrally formed from thematerial comprising the mounting region located along a perimeter of theaperture; positioning the projecting portion at an angle with respect tothe mounting region; and attaching a boss tower to the projectingportion.
 6. The method of claim 5 wherein the step of attachingcomprises adhesively bonding the boss tower to the projecting portion.7. The method of claim 5 wherein the step of attaching comprises weldingthe boss tower to the projecting portion.
 8. The method of claim 5wherein the step of attaching comprises forming a fastening mechanismadapted to attached the boss tower to the projecting portion.
 9. Themethod of claim 5 wherein the step of attaching comprises injectionmolding the boss tower in place over the projecting portion.
 10. Themethod of claim 5 wherein the projecting portion comprises a continuousstructure.
 11. The method of claim 5 wherein the projecting portioncomprises a discontinuous structure.
 12. The method of claim 5 whereinthe step of attaching comprises using the projecting portion to positionand align the boss tower relative to the aperture.
 13. The method ofclaim 5 wherein the step of attaching comprises mechanicallyinterlocking the boss tower with the projecting portion.
 14. The methodof claim 1 wherein the steps of providing a first layer comprising amounting region with an integral boss tower, comprises the steps of:forming an aperture in the mounting region; creating a plurality ofholes around the aperture in the material comprising the mountingregion; and attaching a boss tower to the holes in the mounting region.15. The method of claim 14 wherein the step of attaching comprisesadhesively bonding the boss tower to the mounting region such that theadhesive flows into at least a portion of the holes.
 16. The method ofclaim 14 wherein the step of attaching comprises welding the boss towerto the mounting region.
 17. The method of claim 14 wherein the step ofattaching comprises forming a fastening mechanism adapted to attachedthe boss tower to the holes in the mounting region.
 18. The method ofclaim 14 wherein the step of attaching comprises injection molding theboss tower in place over the holes in the mounting region.
 19. Themethod of claim 14 wherein the step of attaching comprises using theholes in the mounting region to position and align the boss towerrelative to the aperture.
 20. The method of claim 14 wherein the step ofattaching comprises mechanically interlocking the boss tower with theholes in the mounting region.
 21. The method of claim 20 wherein thestep of mechanically interlocking comprises snap-fitting the boss towerwith the holes.
 22. The method of claim 14 wherein the step of attachingcomprises injection molding a boss tower on the mounting region suchthat at least a portion of a material from which the boss tower ismolded flows through the holes.
 23. A method of forming a multi-piecehead suspension for a rigid disk drive, comprising the steps of:providing a first layer comprising a mounting region with an integralboss tower attached to a rigid region by at least one positioning tab;attaching a second layer comprising a spring region at an interfacebetween the mounting region and the rigid region; attaching a flexure tothe rigid region; and removing the at least one positioning tab.
 24. Amethod of forming a multi-piece head suspension for a rigid disk drive,comprising the steps of: providing a first layer comprising a mountingregion and a rigid region; forming an aperture in the mounting region;creating at least one projecting portion integrally formed from thematerial comprising the mounting region located along a perimeter of theaperture; attaching a boss tower to the projecting portion; providing asecond layer comprising a spring region; attaching the second layer tothe first layer so at least a portion of the spring region is located atan interface between the mounting region and the rigid region; andproviding a flexure on the rigid region.
 25. A method of forming amulti-piece head suspension for a rigid disk drive, comprising the stepsof: providing a first layer comprising a mounting region and a rigidregion; forming an aperture in the mounting region; creating a pluralityof holes around the aperture in the material comprising the mountingregion; attaching a boss tower to the holes in the mounting region;providing a second layer comprising a spring region; attaching thesecond layer to the first layer so at least a portion of the springregion is located at an interface between the mounting region and therigid region; and providing a flexure on the rigid region.